Photoelectrically controlled system for detecting suspended matter in fluids



R Z R.J Y 5 l w T 8 [ll WT, M/m 9 E W .....|..|.m|..| N 0 0 E .,W//...-..,, m H T 2 .1 ml n m R H w m G E E C s Z Y 2 R P a Y H B H. C. GRANT, JR PHOTOEILECTRICALLY CONTROLLED SYSTEM FOR DETECTING SUSPENDED MATTER IN FLUIDS Dec. 2, 1952 Filed Nov. 30, 1949 ZMLO . WK kmhov w H. C. GRANT, JR PHOTOELECTRICALLY CONTRQLLED SYSTEM FOR QQN NH DETECTING SUSPENDED MATTER IN FLUIDS Patented Dec. 2 1952 PHOTOELECTRICALLY CONTROLLED SYS- TEM FOR DETECTING SUSPENDED MAT- TER IN FLUIDS Harry C. Grant, Jr., Ridgewood, N. .L, assignor to Specialties Development Corporation, Belleville, N. J a corporation of New Jersey Application November 36, 1949, Serial No. 130,306

17 Claims.

This invention relates to improvements in electroresponsive condition indicator and is particularly directed to apparatus for detecting the presence of suspended matter in fluids and in an electrical supervisory system therefor.

More specifically, the invention is directed to the detection of the presence of smoke in the air of one or more protected spaces or areas, such as fur vaults, record vaults, air ducts, storage rooms, or other space or general area requiring protection against fire, through the detection of smoke. It is to be understood, however, that this invention may be employed for other purposes, as for detection of the presence of suspended matter in other fluids, or for determination of the density of iiuids in containers or enclosures or the like.

When the invention is utilized for the detection of smoke and the giving of an alarm when smoke is detected, smoke detecting apparatus of the photoelectric cell type is employed. One such type of apparatus, whichwill be employed herein for purposes of illustration and description, generally includes a light source or detector lamp and a lens system for directing rays of light on the photoelectric cell, whereby the cell will generate an electric current, the magnitude of which is reduced by the presence of smoke in the path of the rays of light, thereby actuatin a relay to effect the closing of a circuit to an alarm.

In smoke detecting apparatus of the character indicated, When employed to protect spaces or areas where smoke producing hazards exist, control devices and equipment, such as alarm equipment, controls for fire extinguishing systems, and other safety apparatus, in many installations, are connected in with an existing central service staticn, so that trouble and fire alarms are transmitted to the station, and the operation of the fire extinguishing system and other safety apparatus is effected. In such installations, it is of utmost importance that a minimum of trouble signals and no false fire signals be transmitted to the station, inasmuch as such stations are generally remotely situated with respect to the protected spaces or areas and it is the practice at such stations to dispatch a service or repair man to the protected space or area each time a trouble alarm is received, and to notify the city fire department when a fire alarm is received.

Accordingly, it is one of theobiects of the present invention to provide a smoke detecting system which is adapted to be connected to central service station control equipment, and which is fully supervised, Jwhereby to prevent the transmission of false fire alarms to the station and to 2 reduce to a minimum the number of trouble sisnals transmitted to the station.

Another object resides in the provision of a system of the character indicated having electric circuits and instrumentalities which are automatically operable for the supervision of the system and apparatus against various kinds of trouble which may be encountered under actual operating conditions or when the system is conditioned for operation;

Another object of the invention is the provision of a system of the character indicated wherein the functions performed by the smoke detector are completely isolated electrically in their tie-in with the central service station controls, and wherein the system can be connected to the central service station equipment regardless of whether such connections require open or closed electric circuits.

Another object of the invention is the provision of a system wherein, in addition to controlling the central service equipment, provision is also made for controlling local alarms.

A further object is the provision of means whereby, in addition to the giving of alarms, additional functions may be initiated at the control station when a fire alarm is given, such as discharging a, fire extinguishing medium into the protected space or area, shutting down motors, shutting off ventilating systems, closing doors and windows, and operating other safety devices that may be provided.

Other and further objects of the present invention will be obvious as the invention is described in greater detail in connection with the accompanying drawings, in which:

Figure 1 is a schematic view of one type of smoke detecting apparatus suitable for use with the apparatus of the present invention.

Figure 2 is an elevational view of a cabinet for housing the controls of the supervisory system, showing the door of the cabinet open and exposing to view the control panel therein; and

Figure 3 is a wiring diagram of the electrical system of the present invention.

Referring to the drawings in detail, and first to Figure 1, wherein there is schematically illustrated a hollow tube I8, having its ends sealed and provided with a fluid inlet 12 and a fluid outlet hi. A light source or detector lamp I6 and a lens i8 are mounted within the tube at one end thereof and a photoelectric cell 20 is mounted within the tube at the other end thereof. A blower 2'2 or other suction device is provided in the fluid outlet for drawing fluid, such as air or smoke laden air, from a source connected to the inlet 22 through the tube 10 in the path of light from the light source falling on the photoelectric cell.

Terminals 68 and 62 of the detector lamp l8, and terminals E i and 66 of the photoelectric cell 28 are electrically connected to corresponding terminals on a control panel 68, shown in Figure' 2.

The control panel 68, shown in Figure 2, is mounted in a cabinet 70 provided with a door 72 hinged thereto, which may be closed and locked against unauthorized tampering. The door, when closed, engages a button 14 to effect the closing of door switches 76, 18 and 80 (Fig. 3) the button being spring actuated, whereby to open the said switches upon opening of the cabinet door. A local fire alarm silencing switch 82 is mounted on the outside of the cabinet 16, rendering the same readily available without opening the cabinet door.

Terminals (Figure 3) are mounted on the control panel at one side thereof and are electrically connected to local station equipment; while other terminals are mounted on this panel at the other side thereof and are electrically connected to central service station equipment, as will be described hereinafter.

The control panel also has mounted thereon a plurality of relays, shown in Figure 3, designated A to H inclusive, and J to M inclusive; 2. thermal time delay switch N; a local trouble lamp 8 2; a local fire lamp 86; a power switch 88; knobs 90 and 92 for manually effecting the adjustment of a coarse rheostat 96 and a fine rheostat 98, respectively; a thermal time delay switch N; a dirt and fire relay Q; a photoelectric cell circuit supervisory relay S. Windows I and it! are provided in the door of the cabinet 70 through which the pointers of the relays Q and S, respectively, may be viewed. A reset switch button its is also mounted on the control panel for manually effecting the resetting of the relays Q and S, all of which will be referred to hereinafter.

For convenience of description, the several relays will be designated herein by the function they perform, the relay A being lamp supervisory relay, relay B being the trigger relay for circuit set-up relays C, D and E, the relay F being the control relay for a reset solenoid P which functions to reset the fire and dirt relay Q, the relays G and L being the fire signal relays, H being the cell circuit supplementary supervisory decontrol relay for the dirt and fire relay, J being the no voltage release relay, K the trouble relay, M the auxiliary equipment control relay, and R the reset solenoid for the cell supervisory relay.

The photoelectric cell 20 illustrated in the drawings may be of any well known type, but for purposes of illustration and description the cell shown is of the current generating type, so that when the rays of light from the detector lamp it are directed thereon, current will be generated by the cell, the magnitude of the current depending upon the intensity of the light rays received by the cell.

The characteristic of the average photoelectric cell is such that, upon an increase in the ambient temperature, the current output of the cell decreases, so that in the absence of some means to compensate for such decrease a false signal may be transmitted. In like manner, a decrease in the ambient temperature causes the output of the cell to increase, which might, under certain conditions, prevent the transmission of a signal. The present invention provides means for compensating for variations in the current output of the cell due to variations in the ambient temperature, in the nature of a thermo-sensitive resistor ii, mounted adjacent the photoelectric cell 29, which as will be seen from Figure 3, is connected in series with the detector lamp It. This resistor has a negative temperature coefficient such that its resistance decreases on an increase in temperature. The resistance of the resistor 44 being too high to be put directly in series with the detector lamp, a variable resistor 46 is connected in parallel with the resistor to provide the required low resistance value. As the ambient and cell temperature increases, the current output of the cell decreases, but at the same time the resistance of the resistor i l will decrease, whereby the detector lamp will burn brighter to maintain the output current of the cell substantially uniform during normal operation of the system.

Referring now to the wiring diagram of Figure 3, wherein the control panel wiring for the system is illustrated, certain of the local apparatus and instrumentalities connected to the control panel are shown in dotted lines and designated by legends, while auxiliary apparatus, terminals and instrumentalities at the central station are not shown but are designated by appropriate legends. In the'diagram, the various positions designated by the letter X, shown at several points, are all points of the same voltage potential and are to be considered as being connected to each other and to the main voltage supply terminal X, and the various positions designated by the letter Y are to be considered as being connected to each other and to the main voltage supply terminal Y, the lines forming these connections having been omitted from the drawing for the purpose of clarity.

With the system properly installed and before power is applied, all of the relays are in their de-energized positions, as illustrated in Figure 3.

Current for operating the system, with the exception of isolated circuits terminating at the central service station, which will be described later, is supplied from a volt, 60 cycle line controlled by the main power switch 88, which, when closed, connects a number of circuits to the source of current supply, as will be described in more detail hereinafter.

Circuits established upon conditioning the system for operation When the main power switch 88 is closed, certain circuits are established to effect operation of certain relays and instrumentalities whereby to condition the system for operation. During the conditioning of the system, certain signals are given, but these signals will be cleared after the system has been completely conditioned for operation.

When properly installed and current applied to the system, it is in condition to give appropriate signals in the event of fire, or in the event of any trouble for which the system is designed to supervise. The appropriate signals are given through the closing of certain circuits and the consequent operation of relays and other instrumentalities, as will be described in detail hereinafter. I

The circuits established upon conditioning the system for operation will first be described.

A circuit to the detector lamp I6 is completed when the power switch 88'is cldsedwhich circuit maybe traced from terminal T -l of the secondary of a constant'voltage transformer [06' (the primary of which is connected to terminals T-3 and T 4, which in turn are connected to the main voltage supply terminals Xfand Y,respectively), thence through line 200, the coarse adjustable rheostat 96, the fine adjustable'rheostat 98, to terminal 60, through the detectorlamp [6, to terminal 62, 'throughline' 202, the coil of the detector lamp supervisoryfrelay A,'and to terminal T-Z of the secondary of the transformer H16, whereby the detector lamp is lighted and the relay A is energized. At this time current will also flow through the resistor 44, which is in series with the detector lamp. The lighting of the detector lamp causes rays of light'to be directed upon the sensitive element of the photoelectric cell 25, resulting in the generation of current by that cell, which current is delivered through the dirt and fire relay 'Q and'the photoelectric cell circuit supervisory relay S, whereby to operate those relays in the manner about to be described.

Current generated by the photoelectric cell flows in a closed circuit which may be traced from terminal 65 through'line 204, the coil of the photoelectric cell circuit supervisory relay S, line 286, and the coil of the dirt and fire relay Q to the other terminal 64, whereby to energize the relays s and Q to hold open their respective contacts S-l and Q4. The photoelectric cell circuit is shunted by a condenser V, which preferably is of the electrolytic type, but which may be of any other suitable type. This condenser is connected across the terminals 6 and 65 of the photoelectric cell 20, whereby to provide a time delay in the establishment of a normal current output of the photoelectric cell.

The relays Q and S are preferably of the ma netic contact type and, therefore, physical separation of their contacts is required; which separation is effected initially when the circuits to respective reset solenoids P and R are established and those solenoids are thereby operated, as will be described hereinafter.

Thus, when the power switch 88 is closed, a circuit is established through the automatic reset control relay F, which may be traced from the voltage point X adjacent the relay J, contact J-d, lines 288 and 2H and the coil of the relay F to the voltage point Y, whereby the re lay F is energized. The operation of the relay F closes its contact F-3, thereby establishing a circuit to the reset solenoid P, from the voltage point X adjacent the relay F, contact F-3, line M2, and the coil of the solenoid P to the voltage point Y. A circuit to the reset solenoid R is'established directly, upon the closing of the power'switch 88, from the voltage point X adjacent the relay J, the contact J4, lines 208, EM and H6, and the coil of the solenoid R to the voltage point Y.

When the power switch 88 is closed, a circuit is also established directly to the motor 52 of the blower 22, whereby the blower is set in operation. As soon as the blower has established normal suction, a blower supervisory switch N38 is closed thereby. The closing of this switch establishes a circuit to a trouble si'gnal'control relay K, which circuit maybe [traced from the main voltage supply'terminal X to terminal T-l, through the closed blowersupervisory-switch N18, to terminal T-8, thence through line H8,

closed contact I-I-Ei of relay H, line 220, contact A-5 of the already energized lamp supervisory relay A, lines 222 and 224,- contact E-4 of the circuit set-up relay E, lines 226 and 228, contact F-E- of the automatic reset control relay F, line 238, and the coil of the trouble signal relay K to the main voltage supply terminal Y, whereby the relay K is energized. This circuit normally holds the relay K in operated position when the system is conditioned for operation.

The operation of the relay K closes its contactK-Zi, thereby establishing a circuit to contacts for the central station trouble signal, which circuit may be traced from the central station battery terminal CS2D,-through line 232, contact K-5, line 235, door switch 18, and line 238 to the terminal (IS-23 of the central service station trouble signal, through the trouble signal to the other terminal CS-22 of the latter signal, and thence to the other side of CS-Zl oi the battery. This circuit remains closed, when the system is conditioned for operation, by reason of the energization of the relay K, and is adapted to be opened at the time of trouble.

The closing of the power switch 88 also completes a circuit to the local trouble lamp 84, which circuit is closed when the relay K is in de-energized condition. This circuit may be traced from the voltage point X adjacent the relay K, through contact K4 of the de-energized relay K, line 240, and through the trouble lamp 84 to the voltage point Y, whereby that lamp is lighted when the power switch is closed and the relay K de-energized.

When the relay K is energized, upon the closing of the blower supervisory switch 108, which establishes the circuit to that relay in the manner previously described, the contact K-4 is opened, thereby opening the circuit to the trouble lamp 84 to extinguish the same.

Upon closing the power switch 88, a circuit is also established to a thermal time delay switch N from the voltage point X adjacent relay J, through contact J-S, line 242, and the heating element of the switch N to the voltage point Y. After several seconds time delay, the switch N will close its contact N-5, thereby closing a circuit through the relay J from the voltage point X adjacent the thermal time delay switch N, the contact N-5, lines 244 and 245, and through the coil of relay J to the voltage point Y, whereby to energize the relay J, the operation of which will cause the opening of contact J-B, thereby interrupting the circuit to the heating element of the switch N and at the same time closing a holding circuit to the relay J from the voltage point X adjacent the relay J, through the contact J-3, and the coil of the relay J to the voltage point Y.

The time delay effected by the thermal switch N is sufficient to delay the operation of the relay J until after the reset solenoids P and R have operated to effect the initial opening of the dirt and fire relay Q and the photoelectric cell circuit supervisory relay S, respectively.

When the circuit to the heating element of the switch N is interrupted and that element cools, the switch N opens, but the relay J is held operated by its own holding circuit. The operation of the relay J opens its contact J-4, thereby efiecting the opening of the previously described circuits to the relay F and the reset solenoids P and R. During the time delay effected by the thermal switch N, normal current will have been built up in the coils Q and S, causing their respective contacts Q-l and 8-1 to be held open.

When it is desired that various operations be electrically controlled at the time a fire alarm is given, such as the releasing of a fire extinguishing medium into the protected space or area, the closing of doors or windows, or the operation of other safety devices, an independent power supply may be connected to terminals 08-!!! and CS-IQ of the central service station equipment, and, if the operation to be effected requires the closing of a circuit, connections are made to normally open terminals CS-Id and CS-l5, which operate from power applied to terminals CS-IS and CS-l9. If, on the other hand, the operation to be effected requires the opening of a circuit, the connections are made to normally closed terminals CS-IB and 08-11.

The circuits and instrumentalities for eiiecting the operations at the control station are not shown, as these may be of any well known design.

The power supply, as furnished by the central service station, is connected to the terminals CS-Zt and CS-Zl, which supply may be from a dry cell battery located at the protected area and connected across the terminals (IS-20 and CS-Zl. A central service station trouble signal circuit is connected to terminals CS-22 and (ZS-23, which circuit is normally closed when the system is conditioned for operation and is adapted to be opened at time of trouble; and a fire signal circuit is connected to terminals CS-24 and CS-ZE, which circuit is normally open and adapted to be closed at time of fire.

The trouble and fire signals at the central service station may be of any conventional type, such as signal lights on a central service station control panel, audible alarms or the like.

The circuits and connections thus far described are those which are established in order to condition the system for operation, and as will be seen, when the power switch 88 is closed, certain circuits, as previously mentioned, are established from the source of electric current supply to certain of the relays and other instrumentalities, whereby to efiect their operation in conditioning the system for operation.

The closing of the power switch 88 directly establishes circuits to the detector lamp It and its supervisory relay A, the motor of the blower 52, the relay F and the reset solenoid R, the trouble lamp 84, and the thermal time delay switch N, in the manner previously described.

Upon operation of the relay F, a circuit is closed to the reset solenoid P, as previously described. The closing of the circuit to the reset solenoid P efiects the opening of the contact Q-l of dirt and fire relay Q, and the closing of the circuit to the solenoid R effects the opening of the contact of the photoelectric cell circuit supervisory relay S, as also previously described. The time delay efiected by the heating of the element of the thermal switch N is of a few seconds duration, which is sufficient to charge the condenser V, to permit normal current to be built up in the photoelectric cell circuit and to flow through the coils of'the dirt and fire relay Q and the supervisory relay S, whereby these relays will operate to hold open' their respective contacts Q-i and S-l, which were opened by the reset solenoids P and R, respectively, in the manner previously mentioned.

Upon the closing of the contact N-l of the thermal switch N, the holding circuit for the relay J is established, thereby operating that relay to efiect the opening of its contact J-E and the consequent opening of the circuit to the thermal switch N. The opening of the contact J-4 opens the circuit to the reset solenoid R and also the circuit to the relay F, the release of which, in turn, opens its contact F-3, thereby opening the circuit to the reset solenoid P; the energization of the solenoids R and P being no longer necessary due to the operation of the relays Q and S, previously described.

The release of the relay F efiects the closing of its contact F-ii, whereby a circuit is established to the relay K, through the supervisory switch I28, which switch during the aforementioned time delay was closed upon the blower having reached its normal suction. This circuit may be traced from the terminal X of the power switch 88, through the closed blower supervisory switch 98, line 2l3, contact Iii-6, line 228, contact A-5, lines 222 and 22 3, contact Iii-4, lines 22% and 228, contact F-B, line 23%, and the coil of the relay K to the voltage point Y. The operation of the relay K opens its contact K- i, which in turn interrupts the circuit to the trouble lamp 8 thereby indicating that the system is conditioned for operation.

If necessary, the rheostats 9t and 98 may be adjusted manually by rotating the knobs 9t and 92, respectively, whereby to properly position the pointers of the relays Q and S.

With the relays A, J and K energized, the system is in condition for operation to detect the presence of smoke in the supervised space or area, and to supervise the system and detecting apparatus against various kinds of trouble that may be encountered.

Circuits established upon operation of the system Upon operation of the system to give appropriate signals because of fire or due to any other cause for which the system is designed to operate, certain circuits are established and relays and other instrumentalities operated for the transmission of the signals to the local and cen tral service stations.

Most of the signals are initiated upon the ClOSlIlg of the contact Q-! of the dirt and fire relay Q, and accordingly, the operation of that relay will first be described.

As the name implies, the dirt and fire relay Q serves a dual purpose. It causes a trouble signal when the current output of the photoelectric cell is reduced to a pre-set value due to the accumulation of dirt or dust on the optical apparatus; and it causes a distinctive fire signal if the 0611 output is reduced to a still lower pre-set value due to smoke. Since the relay Q is provided with only one set of contacts and is, in itself, adjusted to close these contacts at one definite current value, means must be provided to distinguish two different reduced values of current output of the photoelectric cell and to selectively cause operation of either trouble or fire signals.

If dust or other non-smoke condition (excepting a broken wire or short circuit) causes the reduction in current output of the photo-electric cell, the rate of reduction will be relatively slow, eventually reaching the higher pre-set current value, to cause operation of relay Q, in turn causing a trouble alarm. If the reduction is allowed to persist at the same rate a false fire alarm would eventually result, when the second or lower pre-set current value is reached, but this would ordinarily require many days. On the 9 other hand,'if smoke causes the current reduction, the drop in current will be to the lower preset current value almost immediately, causing first a trouble signal, quickly followed by a fire,

signal. The higher pre-set current value is close enough to the normal current value to obviate the possibility of usual smoke density causing a trouble alarm without dropping the current value enough to cause a fire alarm. The basic scheme to provide this selectivity with a relay having a fixed current closing value is to use a self-controlled shunting resistor. Purely for descriptive purposes, it may be assumed that the relay is adjusted to close at 81 current units or less. If the normal total output of the photo-electric cell is assumed to be 100 units, the shunt may be adjusted to by-pass units, leaving 90 units passing thru the relay to hold the contacts open, with a margin of 9 current units. If dust or other causes result in a reduction of the output of the cellto 90 units, then only 81 units will flow through the relay Q, causing it to close its contacts to result in a trouble signal, disconnecting a shunt across the relay Q andactuating a reset solenoid for that relay, as will be later described in detail. Removal of the: shunt will permit all 90 units (neglecting the slight change in photoelectric cell output which results due to the change in the external circuit resistance through removal of the shunt) to pass through the relay, causing it tohold the contacts open, with a margin of 9 current units. The trouble signal will persist, however. If the cell output continues toreduce to 81 units or less, the relay Q will operate again, this time cutting off the trouble signal and causing a fire alarm signal.

With the foregoing explanation in mind, it will be seen from Figure 3 that the shunt just mentioned is in the form of a resistor H0 provided around the coil of the dirt and fire relay Q. When the current output of the photoelectric cell is normal, that is, at about 150 microamperes, part of the current is shunted around the coil of the relay Q. This resistor may be adjusted, for example, so that when the current output of the photoelectric cell falls to 140 microamperes, the coil Q will release to permit its contact Q-i to close.

The drop in the current output of the cell may be due to an accumulation of dirt or dust in the optical system or to the presence of smoke in the detecting apparatus or to some other cause, as will be determined by the signal given.

In the event the closing of the contact Q-l is due to trouble, as for example the slow accumulation of dust or dirt in the optical system, a trouble signal will be transmitted, and the contact will remain closed until the trouble is rectified. If, however, the closing of the contact is due to fire in the protected space or area, the closing of the contact will automatically establish circuits to effect resetting to open position and remove the shunt around the coil Q, whereby the contact will immediately close a second time and transmit a fire alarm.

The circuits initially established upon the closing of the contact Q-l will now be described.

When the contact Q-I of the dirt and fire relay is closed, a circuit is established to control relay B from the voltage point X adjacent the relay J, through contact J-3. of the relay J, lines 245 and 248, contact H- i, line 250, the closed contact A-2 of the relay A, thence through line 252, the closedv contact Q-i of the dirt and fire relay Q, line 254, contact 3-6 of the r y l 10' 25B, and the coil of the relay B to the voltage point Y, whereby the relay B is energized.

The operation of the relay B, to close its contacts, establishes a circuit to the relays C and D, which may be traced from the voltage point X adjacent the relay J, through contact J-3, lines 246 and 248, contact H-4 of the relay H, line 25a, contact 3-3 of the relay B, lines 260 and 262, contact 0-3 of the relay C, the coil of relay C to the voltage point Y; and from line 260, through the coil of the relay D to the voltage point Y, whereby both the relays C and D are energized. Upon operation of these relays a holding circuit for each is established through the closing of the contact 0-3, which circuit may be traced from the voltage point X adjacent reset button [9d, through line 264, contact C-3, and the coil of relay 0 to the terminal Y, and from contact 0-3 through lines 262 and 260, and the coil of the relay D to the voltage point Y.

The previously described circuit to the relay P, which was established upon the closing of the power switch 88, having been opened upon the operation of the relay J, a new circuit is established to the relay F upon the closing of the contacts Q-l and the consequent operation of the relay D, closing its contact D-3. This new circuit to the relay F may be traced from the voltage point X adjacent the relay J, through contact J-3 of the relay J, lines 246, and 248, contact E4 of the relay H, line 250, contact 13-5 of the relay B, line 266, contact D-3 of the relay D, line 268, and the coil of the relay F to the voltage point Y.

Operation of the relay D, and the consequent opening of its contact D-G, effects the opening of the circuit to the resistor I0 I, to remove the shunt from the coil of the relay Q.

Operation of the relay F effects the closure of its contact F-3, whereby a circuit is closed to the reset solenoid P, from the voltage point X adjacent the relay F, through contact F-3, line 212 and the coil of the solenoid P to the voltage point Y, whereby the reset solenoid P is operated to effect the opening of the dirt and fire relay contact Q|. The opening of this contact breaks the holding circuit of the relay B, previously described, whereby the relay B is released.

The release of the relay B establishes a circuit to the relay E, from the voltage point X adjacent the relay J, through the contact J3, lines 246 and 248, contact H-4 of the relay H, line 25!), contact 345 of the relay B, line 210, contact C-5 of the relay C, line 212, and the coil of the relay E to the voltage point Y.

Operation of the relay E, and the consequent opening of its contact Eel, opens the circuit to the relay K, which thereby releases and efiects the closure of contact K4 to close the circuit to the trouble lamp 84. The release of the relay K will efiect the opening of the contact K-S whereby to open the normally closed circuit to the central station trouble signal.

When the total current flow in the photoelectric cell circuit through the dirt and fire relay Q, after the removal of the shunt, is suficient to hold the contact Q-I of the relay open, no further action takes place, but the trouble lamp will remain illuminated by reason of the release of the relay K just described. However, when the shunt circuit has been opened upon the energization of the relay D, and when the current flow in the photoelectric cell circuit through the relay Q has been reduced to such an extent that the relay Q cannot hold the contact Q-i open,

the contact Q-l will again close and thereby establish circuits to the fire alarm control relays G and L, which circuits may be traced from the voltage point X adjacent the relay J, contact J-3 of the relay J, lines 246 and 248, contact H-d of the relay H, line 259, contact A-3 of the relay A, line 252, contact Q-l, line 254, contact E-e, lines 214 and 216, and the coil of the relay G to the voltage point Y, and through the line 2'58, and the coil of the relay L to the voltage point Y, whereby the relays G and L are operated. It should be noted that, if desired, the relays G and L can be replaced by a single relay having surficient contacts, but two are used to permit standardization on relay requirements.

Closure of the contact G- shunts out the opened contact E-t of the operated relay E, and reestablishes a circuit to the relay K, whereby to open the circuit to the trouble lamp 8:") and eifect extinguishment of that lamp, and at the same time closes the contact K-5 to close the normally closed circuit to the central station trouble signal. However, operation of the central station trouble signal is only momentary, that is, until the fire signal relays are operated in the manner just described to transmit a fire signal to the central station, which renders the central station trouble signal ineffective.

The reestablished circuit to the relay K may be traced from the terminal X adjacent the power switch 33, through terminal 'I l, the 131027- er supervisory switch 163, terminal T3, line contact 1-1-6 of the relay H, line 226, contact i-5 of the relay A, lines 222 and 28%, contact G-5, lines 282 and 228, contact F-6 of the relay F, line 239, and the coil of the relay F; to the voltage point Y.

Closure of the contact L-B of the relay L establishes circuits to the local fire lamp, the local fire signal and the fire signal at the central station. The circuit to the local fire lamp may be traced from the voltage point X adjacent the relay L, contact L-3 of the relay L, line the closed door switch 16, line 285, and through the local fire lamp 8% to the voltage terminal Y. The circuit to the local fire signal may be traced from the line 285 and the line 283 through the local fire alarm silencing switch 82, line 29%, terminal T-Hl, through the local fire signal H2 and terminal T-S, to the terminal Y. The circuit to the fire signal at the central station may be traced from battery terminal 08-26, lines 232 and 292, contact L-5 of the relay L, line 2%, door switch 89, line 2%, to terminal GEE-25 or the fire signal, through the central station fire signal, thence to the terminal CS-2 l and the other ter minal CS-Zl of the battery.

The operation of the relay L also establishes a circuit to the auxiliary equipment control relay M, from the voltage point X adjacent the relay L, contact L-3, line 284, the door switch 15, line 298, and the coil of the relay M to the voltage point Y. The relay M is provided to efiect the closing of circuits to auxiliary equipment, such as operating mechanisms for dis charging a fire extinguishing medium into the protected space or area, for closing windows and doors, for shutting down blowers, and for the operation of any other safety devices or mechanisms that may be provided, the operation of which is desired upon the outbreak of fire, which devices or mechanisms are electrically connected to the normally open terminals (36-! :3 and CS4 5, or the normally closed terminals CS-it and CS-l'l, and to the poles or terminals (ZS-i8 and CS-IQ. The operation of the relay M, and the 12 consequent opening or closing of its contacts M-3, M-4, M-5 and M6, as will be obvious from the wiring diagram, establishes circuits to the said terminals and poles.

Operation 07' system The operation of the system is as follows:

As previously mentioned, under normal oper ating conditions, the current output of the photoelectric cell 20 is 150 microamperes, and part of the current is shunted through the resistor I [0 around the coil of the dirt and fire relay Q. This resistor is adjusted and fixed so that in the event the photoelectric cell current output is reduced to microamperes, the cur rent fiowing through the coil of the dirt and fire relay Q will be insufiicient to hold its contact Q-l open, and the contact will, therefore, close.

The reduction in the current output of the photoelectric cell may be due to a reduction in the intensity of the light rays falling on the photoelectric cell, because of an accumulation of dust or dirt in the optical system of the detecting apparatus, or because of the passage of smoke through the light rays from the detector lamp, which smoke is drawn through the detecting apparatus from the protected space or area by the continuously operating blower 52, in the manner previously described.

The closing of the contact Q-l will close the circuit to the relay B, whereby to operate that relay, which in turn, will close the circuits to the relays C and D. Operation of the relay D opens its contact D-B, thereby removing the shunt from the dirt and fire relay Q. Operation of the relay D also closes its contact D-3, thereby establishing the circuit to the relay F, causing that relay to operate.

The operation of the relay F closes its contact F-3, which in turn, closes the circuit to the reset solenoid P, whereby to effect the reopening of the contact Q-I of the dirt and fire relay Q. The opening of the latter contact will, in turn, open the circuit to relay B, permitting that relay to release. The relays C and D, however, remain energized by the holding circuits previously established.

The release of the relay B establishes the circult to the relay E, causing that relay to operate and open its contact E4 and thereby breaking the holding circuit to the relay K, which thereupon releases, permitting the contact K% to close and causing the trouble lamp 84 to light.

The release of the relay B also opens the circuit to the relay F, the release of which opens the circuit to the reset solenoid P.

With the reset solenoid P de-energized and the shunt removed from the coil of the relay Q, the photoelectirc cell current then flowing through that coil may be sufiicient to hold the contact Q-l open, in which event no further action will take place, but the trouble lamp 84 will remain lighted, indicating to the attendant at the local station that some trouble has developed, such, for example, as the accumulation of dust or dirt in the optical system of the detecting apparatus.

However, in the event the contact Q4 of the dirt and fire relay Q was closed due to smoke being drawn through the smoke detecting apparatus, the reduction of current in the photoelectrio cell circuit will be such that, even with the shunt removed from the coil of the relay Q, the relay can not hold its contact open, and it will, accordingly, close for the second time. Upon this second closing of the said contact, with the relay 13 E now energized, the circuits to the fire relays G and L will be closed.

The closing of the contact Q-I for the second time, due to smoke being drawn by the blower from the protected space through apparatus, and the consequent operation of the relay L, causes the contact L-3 of the latter relay to close, thereby closing the circuit to the local fire lamp 86 and the local fire signal I I 2, thereby causing that lamp to be illuminated and the local fire signal to be given. The operation of the relay L also effects the closingof its contact L-5, thereby completing the circuit from the central service station battery terminal 08-20 to the fire signal at the central service station and actuating that signal.

The operation of the relay L, and the consequent closing of its contact L-3, also closes the circuit to the relay M, the operation of which effects the closing of circuits to the normally open contacts CS-M and CS-IS and opening the circuit to the normally closed contacts CS-I 6 and CS-I I, whereby to effect the operation of the auxiliary equipment at the central service station.

A fire signal having been transmitted to the central service station, the local fire signal I I2 may, if desired, be silenced by manually opening the alarm silencing switch 82.

After the fire has been extinguished, the system may again be conditioned for operation by manually pressing the reset button I04.

In the event that the external wiring connecting the photoelectric cell to the control panel is cut, or is short circuited due to a ground, current from the cell will be immediately cut off, causing the closing of the contact S-I of the photoelectric cell supervisory relay S. Under such conditions, this contact will close before the closing of the contact Q-I of the dirt and fire relay Q. This is due to the condenser T, which is connected across the coil of the relay Q, and which will hold the current through the latter coil for a considerable period of time; no such condenser or other time delay device being provided for the relay S. The closing of the contact S-I of the relay S establishes a circuit through the relay H, causing that relay to operate. The operation of the relay H, and the consequent opening of its contact H 5, will break the holding circuit to the relay K, causing the latter relay to release and effect the closing of the circuit to the local trouble lamp 84. The release of the relay K will also cause the contact K-6 to open, thereby opening the normally closed circuit to the central station trouble signal. Upon closing of the circuit to the local trouble lamp it will be lighted, and upon the opening of the circuit to the central service station trouble signal that signal will be operated. The opening of the contact H- l, upon operation of the relay H, also breaks the circuit to the relays G and L, so that, when the condenser T has been discharged sufiiciently and the con tact Q-I of the relay Q closes, the relays G and L cannot operate to transmit a false fire alarm to the central station.

An extremely heavy surge smoke through the detecting apparatus sufiicient to substantially block the light rays from the photoelectric cell would, in eifcct, be equivalent to the cutting of the external wiring or short circuiting of the photoelectric cell, just mentioned. In such event, however, the condenser V, which is connected across the photoelectric cell, will distinguish between heavy smoke and a broken wire or short circuit. In the event of a broken wire or short Cir 14 circuit, the. condenser. V will be rendered ineffective'andwill discharge rapidly, whereas, in the event of heavy smoke blocking the light rays from the photoelectric cell, the condenser V will discharge relatively slowly, thereby permittin the contact 63-1 of the dirt and fire relay to closetWice in rapid succession and transmit the necessary fire signals, in the manner previously described, before the contact S-I can close to effect the operation of the relay H and the transmission of trouble signals. Accordingly, when the smoke drawn from the protected space or area through the detecting apparatus is of sufiicient density to substantially block the rays of light, emitted by the detector tube, from the photoelectric cell, a fire signal is transmitted to both the local and central stations, Without first transmitting efiective trouble signals, which signals in such event'would be false trouble signals.

The relays C and D, which are electrically locked in operating position following the first operation of the dirt and fire relay Q, may be released manually by operating the reset button IM, thereby breaking the holding circuit. Operation of this button also directly operates the reset solenoids P and R.

In the event that the detector lamp should burn out, or in the event of a short or ground in the circuit of that lamp, a trouble signal will be transmitted to the local station by reason of the release of the relay A, which results in breaking the circuit to the trouble signal control'rel-ay K. Likewise, in the event of power failure, the relay A will be released with the same result. The trouble lamp will also light in the event of any interruption in the circuit to the relay K.

In the event that the blower 22 should cease operation, or in the event that the suction of the blower should fall to below normal, the blower supervisory switch I68 will automatically open, breaking the circuit to the trouble relay K and thereby effecting the closing of the trouble cir cult and the illumination of the trouble lamp 84.

In the event that the door of the cabinet is opened, a trouble signal will be transmitted to the central service station due to the resultant openin of the door switch I8, which opens the normally closed circuit to the said signal. When the cabinet door is open, no fire signal can be transmitted to the central service station by reason of the open door switch 80, and the relay M will not operate to effect closing of the circuits to the auxiliary equipment by reason of the open door switch I6.

When the system is conditioned for operation, should there be any variation in the photoelectric cell current due to variations in the ambient temperature such variations will be compensated for in the output of the detector lamp I6 by the thermo-sensitive resistor 44.

When it is desired to employ the system of the present invention for the detection of suspended matter in other fluids or to determine the density of other fluids, a container for the fluid to be examined is substituted for the smoke detector tube, where the fluid to be examined is static, or a flow tube is substituted where the fluid to be examined is in circulation. In such detecting apparatus an alarm will be given in the manner described for the trouble alarm when a small quantity of suspended matter is present in the fluid, and an alarm will be given, similar to the fire alarm, when the quantity of the suspendedmatter increases'to a greater extent.

It will be seen from the foregoing that the present invention provides an electroresponsive indicator having means responsive to conditions to be indicated and including a plurality of sig nal means and circuit means including relays independently operable upon the actuation of said responsive means, whereby to eifect the operation of said signal means to indicate a condition identifiable by the operated signal means.

From the foregoing it will also be seen that the present invention provides a fully supervised system for the detection of suspended matter in fluids; a system which can be connected to existing central service stations but which is isolated electrically in the connections to the central service station; a system which will prevent the transmission of false fire alarms and reduce to a minimum trouble alarms transmitted to the service station; a system which will function to effect the initiation oi safety apparatus, such as the discharge of a fire extinguishing medium, the closing of doors and windows and similar operations, upon the outbreak of fire; and a system which is automatically operable to transmit proper signals upon the development of trouble of various kinds which may be encountered under actual operation conditions and when the system is conditioned for operation.

While a preferred embodiment of the invention has been illustrated and described, it is to be understood that the invention is not to be limited to the precise construction and arrangement of parts shown and described, nor to the described sequence of operation of the system, as obviously various changes and modifications may be made therein without departing from the spirit and scope of the invention.

I claim:

1. A system of the class described comprising in combination a detector lamp, an electric circuit therefor, a photoelectric cell responsive to light from said lamp, a photoelectric cell circuit, and second eleotroresponsive means con nested in series in the photoelectric cell circuit operable respectively in response to different variations in the normal current output of said cell, electrically operated signal means, a circuit for said signal means adapted to be closed upon operation of said first electroresponsive means, second electrically operated signal means, a circuit for said second signal means adapted to be closed upon operation of said second electroresponsive means, and thermoresponsive resistor means connected in series with the detector lamp and disposed in juxtaposition to the photoelectric cell for preventing variations in the normal current output of the cell due to variations in the ambient temperature.

2. In a detecting system of the class described, the combination of a light source, a circuit therefor including a source of electrical energy, a photoelectric cell responsive to light from said source, a cell circuit for the output current of said cell, electroresponsive means connected in said cell circuit and operable in response to a variation in the cell current, a signal and a normally open circuit therefor, electroresponsive control means normally holding said signal circuit open, a normally closed circuit for said control means, a relay, an electric circuit established to said relay upon operation of said first electroresponsive means, a second relay operable upon the operation of said first relay to open the circuit to said control means whereby the circuit to the signal will be closed, a shunt circuit in said photoelectric cell circuit across said electroresponsive means, a resistor in said shunt circuit, a third relay for controlling said shunt circuit, a circuit for said third relay controlled by said first relay, and means for resetting the said electroresponsive means and a normally open circuit therefor con trolled by said second relay and closed upon the operation of the second relay to effect the resetting of the said electroresponsive means, the resetting of the latter means efiecting the opening of the circuit to the said first relay and the consequent opening of the circuit to the second relay, thereby elfecting the opening of the circuit to the control means and the consequent opening of the circuit to the signal.

3. In a detecting system of the class described, the combination of a light source, a circuit therefor including a source of electrical energy, a photoelectric cell responsive to light from said source, a cell circuit, electroresponsive means connected in said cell circuit and operable in response to a variation in cell current, a signal and a normally open circuit therefor, electroresponsive control means normally holding said signal circuit open, a normally closed circuit for said control means, a relay, an electric circuit established to said relay upon operation of said first electroresponsive means, asecond relay operable upon the operation of said first relay to open the circuit to said control means whereby the circuit to the signal will be closed, and means for resetting said first electroresponsive means and a normally open circuit therefor controlled by said second relay to efiect the resetting of said first electroresponsive means, the resetting of the latter means effecting the opening of the circuit to said first relay and the consequent opening of the cir cuit to the second relay, thereby effecting the opening of the circuit to the control means and the consequent opening of the circuit to the signal, a shunt circuit in said photoelectric cell circuit across said first electroresponsive means, a resistor in said shunt circuit, a third relay and a circuit therefor controlled by the first relay, whereby upon operation of said third relay the shunt circuit will be rendered effective to vary the current output of the cell passing through said first electroresponsive means, which current output when insuificient to prevent the operation of the said first electroresponsive means will permit the same to operate for a second time, an alarm, and a circuit for said alarm adapted to be closed upon the second operation of said first electroresponsive means.

4. In a detecting system of the class described; the combination of a light source; a circuit therefor including a source of electrical energy, a photoelectric cell responsive to light from said source, and a cell circuit; electro-responsive means connected in said cell circuit and operable in response to a variation in cell current; a signal and a circuit therefor, a first relay normally holding said signal circuit open; a normally closed circuit for said first relay; a second relay; an electric circuit established to said second relay upon operation of said electroresponsive means; a third relay for controlling the said normally closed circuit for the first relay; fourth and fifth relays operable upon the operation of the second relay to establish holding circuits for the fourth relay; a sixth relay operable upon the operation of said second relay to open the circuit to said first relay, whereby the circuit to. the signal will be closed; reset means for said electroresponsive means and a circuit therefor established upon .17 the operation of the said sixth relay for restoring the electroresponsive means to its original position, thereby to open the circuit to the second relay and deenergize the sixth relay to render the reset means ineffective; a shunt circuit in said cell circuit shunting a portion of the current outputof said cell around said electroresponsive means, said shunt circuit adapted to be opened upon the operation of said fifth relay; whereby the said electroresponsive means will be subject to a predetermined value of the current output of said cell sufficient to again operate the electroresponsive means; an alarm relay and an alarm controlled thereby; and a circuit to said alarm relay established upon the second operation of said electroresponsive means.

5. In a detecting system of the class described, the combination of a light source, a circuit therefor including a source of electrical energy, a photoelectric cell responsive to light from said source and a cell circuit therefor, electroresponsive means connected in said cell circuit and operable in response to a variation in the current in said cell circuit, a trouble signal and a signal circuit therefor, a trouble signal control relay normally holding said signal circuit open, a normally closed circuit for said control relay, a trigger relay, an electric circuit established to said trigger relay upon operation of said electroresponsive means, a first set-up relay and a second circuit set-up relay, circuits therefor established upon the operation of said trigger relay, a holding circuit for the first set-up relay established upon operation of that relay, a shunt connected in said cell circuit controlled by the second set-up relay and operable to vary the current output of the cell circuit, a second control relay operable upon the operation of said trigger relay to open the circuit to said control relay, whereby the circuit to the signal will be closed, reset means for said electroresponsive means and a circuit therefor established upon the operation of the second control relay for restoring the electroresponsive means to normal position and for interrupting the circuit to said trigger relay to deenergize the same, whereby the circuit to the second control relay is interrupted reestablishing the circuit to the trouble control relay to effect the opening of the circuit to the trouble signal and interrupting the circuit to the reset means, whereupon when the variation in the current output of the cell circuit effected upon the operation of the shunt by the operation of the second set-up relay is nsufficient to retain the electroresponsive means in its normal reset position the latter means will again operate, a third circuit set-up relay and a circuit therefor established upon deenergization of the trigger relay, 2, fire signal, and a fire signal relay and a circuit therefor established upon the operation of the third set-up relay, whereby upon the second operation of the electroresponsive means the fire signal will be operated.

6. In a detecting system of the class described, the combination of a light source, a circuit therefor including a source of electrical energy, a photoelectric cell responsive to light from said source and a cell circuit therefor, electroresponsive means connected in said cell circuit and operable in response to a variation in the current in said cell circuit, a trouble signal and a normally closed circuit therefor, a trouble signal control relay normally holding said signal circuit open, a normally closed circuit for said control relay, a trigger relay, an electric circuit established to said trigger relay upon operation of said electroresponsive means, a first and a second circuit set-up relay and circuits therefor established upon the operation of said trigger relay, a holding circuit for the first set-up relay established upon operation of that relay, a shunt connected in said cell circuit controlled by the second set-up relay and operable to vary the current output of the cell circuit, a second control relay operable upon the operation of said trigger relay to open the circuit to said control relay, whereby the circuit to the signal will be closed, reset means for said electroresponsive means and a circuit therefor establihed upon the operation of the second control relay for restoring the electroresponsive means to normal position and for interrupting the circuit to said trigger relay to deenergize the same, whereby the circuit to the second control relay is interrupted reestablishing the circuit to the trouble control relay to effect the opening of the circuit to the trouble signal and interrupting the circuit to the reset means, whereupon when the variation in the current output of the cell circuit effectedupon the operation of the shunt by the operation of the second set-up relay is insuflicient to retain the electroresponsive means in its normal reset position the latter means will again operate, a third circuit set-up relay and a circuit therefor established upon deenergization of the trigger relay, a fire signal, a fire signal relay and a circuit therefor established upon the operation of the third set-up relay, whereby upon the second operation of the electroresponsive means the fire signal will be operated, a main power switch connected to a source of electrical energy, a voltage control relay and a circuit therefor, time delay means operable to delay the closing of the circuit of said voltage control relay for a predetermined period after the closing of said main power switch, whereby to permit the said second control relay to operate to effect the operation of said reset means'in conditioning the system for operation.

'7. In a detecting system of the class described, the combination of a light source, a circuit therefor including a source of electrical energy, a photoelectric cell responsive to light from said source and a cell circuit therefor, electroresponsive means connected in said cell circuit and operable in response to a variation in the current in said cell circuit, a trouble signal and a normally closed circuit therefor, a trouble signal control relay normally holding said signal circuit open, a normally closed circuit for said control relay, a trigger relay, an electric circuit established to said trigger relay upon operation of said electroresponsive means, a first and a second circuit setup relay and circuits therefor established upon the operation of said trigger relay, a holding circuit for the first set-up relay established upon operation of that relay, a shunt connected in said cell circuit controlled by the second set-up relay and operable to vary the current output of the cell circuit, a second control relay operable upon the operation of said trigger relay to open the circuit to said control relay, whereby the circuit to the signal will be closed, reset means for said electroresponsive means and a circuit therefor established upon the operation of the second control relay for restoring the electroresponsive means to normal position and for interruptingthe circuit to said trigger relay to deenergize the same, whereby the circuit to the second control relay is interrupted reestab- .lishing the circuit to 19 the trouble control relay to eifect the opening of the circuit to the trouble signal and interrupting the circuit to the reset means, whereupon when the variation in the current output of the cell circuit effected upon the operation of the shunt by the operation of the second set-up relay is insuflicient to retain the electroresponsive means in its normal reset position the latter means will again operate, a third circuit set-up relay and a circuit therefor established upon deenergization of the trigger relay, a fire signal, a fire signal relay and a circuit therefor established upon the operation of the third set-up relay, whereby upon the second operation of the electroresponsive means the fire signal will be operated, and an auxiliary equipment control relay and a circuit therefor established upon the operation of said fire signal relay, whereby to establish circuits for the operation of auxiliary equipment substantially simultaneously with the operation of said fire signal.

8. In a detecting system of the class described, the combination of a light source, a circuit therefor including a source of electrical energy, a photoelectric cell responsive to light from said source and a cell circuit therefor, electroresponsive means connected in said cell circuit and operable in response to a variation in the current in said cell circuit, a trouble signal and a normally closed circuit therefor, a trouble signal control relay normally holding said signal circuit open, a normally closed circuit for said control relay, a trigger relay, an electric circuit established to said trigger relay upon operation of said electroresponsive means, a first and a second circuit set-up relay and circuits therefor established upon the operation of said trigger relay, a holding circuit for the first set-up relay established upon operation of that relay, a shunt connected in said cell circuit controlled by the second set-up relay and operable to vary the current output of the cell circuit, a second control relay operable upon the operation of said trigger relay to open the circuit to said control relay, whereby the circuit to the signal will be closed, reset means for said electroresponsive means and a circuit therefor established upon the operation of the second control relay for restoring the electroresponsive means to normal position and for interrupting the circuit to said trigger relay to deenergize the same, whereby the circuit to the second control relay is interrupted reestablishing the circuit to the trouble control to effect the opening of the circuit to the trouble signal and interrupting the circuit to the reset means, whereupon when the variation in the current output of the cell circuit effected upon the operation of the shunt by the operation of the second set-up relay is insufficient to retain the electroresponsive means in its normal reset position the latter means will again operate, a third circuit set-up relay and a circuit therefor established upon deenergization of the trigger relay, a fire signal, a fire signal relay and a circuit therefor established upon the operation of the third set-up relay, whereby upon the second operation of the electroresponsive means the fire signal will be operated, an auxiliary equipment control relay and a circuit therefor established upon the operation of said fire signal relay, whereby to establish circuits for the operation of auxiliary equipment substantially simultaneously with the operation of said fire signal, a housing for said electroresponsive devices having a door, and switch means operable by said door in the circuit of said auxiliary control relay,

whereby upon opening said door the said switch means will be actuated to effect the opening of the circuit of the auxiliary control relay to prevent the operation of said auxiliary equipment.

9. In a detecting system of the class described, the combination of alight source, a circuit therefor including a source of electrical energy, a photoelectric cell responsive to light from said source and a cell circuit therefor, electroresponsive means connected in said cell circuit and operable in response to a variation in the current in said cell circuit, a trouble signal and a signal circuit therefor, a trouble signal control relay normally holding said signal circuit open, a normally closed circuit for said control relay, a trigger relay, an electric circuit established to said trigger relay upon operation of said electroresponsive means, a first set-up relay and a second circuit set-up relay, circuits therefor established upon the operation of said trigger relay, a holding circuit for the first set-up relay established upon operation of that relay, a shunt connected in said cell circuit controlled by the second set-up relay and cperable to vary the current output of the cell circuit, a second control relay operable upon the operation of said trigger relay to open the circuit to said control relay, whereby the circuit to the signal will be closed, reset means for said electroresponsive means and a circuit therefor established upon the operation of the second control relay for restoring the electroresponsive means to normal position and for interrupting the circuit to said trigger relay to deenergize the same, whereby the circuit to the second control relay is interrupted reestablishing the circuit to the trouble control relay to effect the opening of the circuit to the trouble signal and interrupting the circuit to the reset means, whereupon when the variation in the current output of the cell circuit effected upon the operation of the shunt by the operation of the second set-up relay is insufficient to retain the electroresponsive means in its normal reset position the latter means will again operate, a third circuit set-up relay and a circuit therefor established upon deenergization of the trigger relay, a fire signal, a fire signal relay and a circuit therefor established upon the operation of the third set-up relay, whereby upon the second operation of the electroresponsive means the fire signal will be operated, second clectroresponsive means connected in said cell circuit in series with the first mentioned electroresponsive means, a second fire signal control relay and a circuit therefor established upon the completion of the circuit to the first mentioned fire control relay, means associated with the first electroresponsive means operable under predetermined conditions for delaying the operation of said first electrorespcnsive means until the second electroresponsive means has operated, a cell circuit supervisory relay and a circuit therefor established upon the operation of said second electroresponsive means, whereby to operate the last named relay to interrupt the circuit to said trouble relay whereby to permit the closing of the circuit to the trouble alarm, the operation of the last named relay also interrupting the circuits to said first and second fire signal control relays to prevent the operation of said fire control relays.

10. In a detecting system of the class described, the combination of a light source, a circuit therefor including a source of electrical energy, a photoelectric cell responsive to light from said source,

a cell circuit for the output current of said cell, electroresponsive means connected in said cell circuit and operable in response to a variation in said current, a signal and a normally open circuit therefor, control means including a relay for efiecting closing of said signal circuit and a circuit for said relay established upon operation of said electroresponsive means, a shunt circuit in said photoelectric cell circuit across said electroresponsive means including a resistor, a relay for controlling said shunt circuit, a circuit for said last mentioned relay controlled by said first relay, and means for resetting said electroresponsive means and a normally open circuit therefor including means for effecting closing thereof.

11. In a detecting system of the class described, the combination of a light source, a circuit therefor including a source of electrical energy, a photoelectric cell responsive to light from said source, a cell circuit, electroresponsive means connected in said cell circuit and operable in response to a variation in cell current, a signal and a normally open circuit therefor, control means normally holding said signal circuit open, a relay, an electric circuit for said relay established upon operation of said electroresponsive means, a second relay for operating said control means to effect closing of said signal circuit, an electric circuit for said second relay established upon operation of said first relay, means for resetting said electroresponsive means and normally open circuit therefore controlled by said second relay to effect resetting of said electroresponsive means, the resetting of the latter means effecting the opening of the circuit to said first relay and the consequent opening of said second relay circuit thereby causing said control means to effect closing of said signal circuit, a shunt circuit in said cell circuit across said electroresponsive means, a resistor in said shunt circuit, a third relay and a circuit therefor controlled by said first relay, whereby upon operation of said third relay said shunt circuit will be rendered eifective to Vary the current output of said cell passing through said electroresponsive means, which current when of a predetermined value will permit said electroresponsive means to operate for a second time, an electrically operable element, and a circuit for operating said element adapted to be closed upon the second operation of said electroresponsive means.

12. A detecting system according to claim 11, wherein relay means are connected in said element operating circuit and are conditioned by said first relay to effect closing thereof upon the second operation of said electroresponsive means.

13. A detecting system of the class described comprising in combination a lamp, an electric circuit therefor, a photoelectric cell responsive to light from said lamp, 9. cell circuit including means operable in response to variations in the normal output current of said cell, and thermoresponsive resistor means connected in series with said lamp, said resistor means being located in close proximity to said cell and being arranged to adjust the current supplied to said lamp in response to variations in the ambient temperature adjacent said cell and thereby prevent variations in the normal output current of said cell due to variations in said ambient temperature.

14. A detecting system of the class described comprising in combination a source of light including an electric circuit therefor, a photoelectric cell responsive to light from said source, a photoelectric cell circuit for the output current of said cell, electroresponsive means connected in said cell circuit and operable in response to a variation in said current of a predetermined value, a circuit controlled by said electroresponsive means, relay means in said last mentioned circuit operable upon operation of said electroresponsive means, a shunt circuit in said photoelectric cell circuit across said electroresponsive means including a resistor and being under the control of said relay means to open and close the same to thereby change the output current of said cell normally passing through said electroresponsive means from one predetermined value to another upon an operation of said electroresponsive means whereby a variation in cell output current of another predetermined value is required to effect a second operation of said electroresponsive means, reset means for said electroreponsive means, and circuit means under the control of said relay means including signal means.

15. A detecting system according to claim 14 wherein a condenser is connected across said electroresponsive means.

16. A system of the class described comprising in combination a lamp, an electric circuit therefor, a photoelectric cell responsive to light from said lamp, a photoelectric cell circuit, first and second electroresponsive means connected in series in the photoelectric cell circuit each adapted to respectively control a signal circuit, said first electroresponsive means being operable upon a predetermined variation in the current output of said cell and said second electroresponsive means being operable upon a greater variation in the current output of the cell in the same direction as the first variation, a signal circuit including an electrically operated fire signal device and a normally open switch under the control of said first electroresponsive means, a second signal circuit including an electrically operated trouble signal device and a normally open switch under the control of said second electroresponsive means, condenser means connected across said first electroresponsive means to delay its operation with respect to the time of operation of said second electroesponsive means, and means whereby the operation of said second electroresponsive means before the operation of said first electroresponsive means renders the subsequent operation of said first electroresponsive means ineffective to control said fire signal device circuit.

17. A system according to claim 16, wherein said photoelectric cell has condenser means connected across the terminals thereof.

HARRY C. GRANT, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,115,419 Faller Oct. 27, 1914 1,324,732 Degen Dec. 9, 1919 1,772,671 Lomax Aug. 12, 1930 2,052,057 Reid Aug. 25, 1936 2,362,021 Nazar Nov. '7, 1944 2,444,065 Pouliart June 29, 1948 2,509,497 Hesson May 30, 1950 

